For instance, the piston valve type of two-cycle gasoline engine has its intake/exhaust cycle of an air/fuel mixture controlled by a port in a cylinder and a piston reciprocating within the cylinder. In order to enhance the charging efficiency of the air/fuel mixture in the cylinder, it is thus required that the air/fuel mixture be forced at a high density on the intake side, while a forcing-back action be caused to occur on the exhaust side so as to prevent blowing-through of fresh air from the cylinder. For that reason, as in the two-cycle gasoline engine shown in Laid-open Utility Model No. 55-132321, the two-cycle gasoline engine has been such that an exhaust pipe is formed into a chamber shape narrowed down at the extreme end, and exhaust gases are admitted into that portion at a timing just before an exhaust port is closed, making use of the reflected wave of exhaustion. However, it is impossible to obtain all the tuning (resonance) due to a difference in the revolutions of the engine. For that reason, various means for regulating the phase of the reflected wave in the intake/exhaust system have been taken to obtain the tuning (resonance) of the intake/exhaust pulsation.
That is to say, the exhaust timing, for instance, has generally been varied depending upon the revolutions of an engine, and there has been a system wherein arranged in the vicinity of an exhaust port is a variable regulation valve which is designed to be turned, for instance, when the revolutions of the engine is increased, thereby putting forward the exhaust timing for more satisfactory operation.
In such a conventional system, however, the revolutions of an engine is used as a control factor. Thus, this system is not complete, although it makes it possible to approximately reproduce the timing good for the intake/exhaust efficiencies obtained in advance by calculation or experimentation. In other words, the impedance in the exhaust system, the speed of sound having an influence upon the velocity of a standing wave and all other factors vary actually depending upon the degree of opening of a throttle, temperature of the intake/exhaust system, differences in atmospheric pressure due to elevation differences, changes in the volume of an exhaust chamber or deformation of chamber due to build-ups (carbon), etc. in an exhaust pipe, wearing of an engine and the like. Thus, the fact is that to use only the revolutions of an engine as the control factor cannot accommodate such changes.
The situation being like this, the present invention now develops a novel engine controller which can produce the desired output in every state of operation by directly detecting and controlling pulsation having an immediate influence upon the desired operation of such an intake/exhaust system.